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Tin‐rich Phases RE 2 Au 3 Sn 6 with RE = La, Ce, Pr, Nd, Sm – Synthesis, Structure, Magnetic Properties, and 119 Sn Mössbauer Spectra
Author(s) -
Engelbert Simon,
Janka Oliver,
Klenner Steffen,
Pöttgen Rainer
Publication year - 2020
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201900329
Subject(s) - crystallography , materials science , orthorhombic crystal system , magnetic susceptibility , crystal structure , tin , germanide , electrical resistivity and conductivity , antiferromagnetism , space group , tantalum , x ray crystallography , chemistry , diffraction , condensed matter physics , metallurgy , germanium , physics , optics , silicon , electrical engineering , engineering
The stannides RE 2 Au 3 Sn 6 ( RE = La, Ce, Pr, Nd, Sm) were synthesized from the elements by arc‐melting. Small single crystals were grown by annealing samples in sealed tantalum tubes in an induction furnace with a special annealing sequence. The polycrystalline phases were characterized through their X‐ray powder diffraction pattern. The structures of Ce 2 Au 3 Sn 6 , Pr 2 Au 3 Sn 6 , and Nd 2 Au 3 Sn 6 were refined from single‐crystal X‐ray diffractometer data. The RE 2 Au 3 Sn 6 stannides crystallize with the orthorhombic La 2 Zn 3 Ge 6 type, space group Cmcm . The basic structural building units are Au1@Sn 4 tetrahedra and Au2@Sn 5 square pyramids. These units are condensed to layers and the structure can be described by a simple stacking of tetrahedral and pyramidal layers with the rare earth cations in between. Temperature dependent susceptibility studies indicate that all rare earth atoms are in the trivalent oxidation state, as their effective magnetic moments match the expected values of the free RE 3+ ions. Pr 2 Au 3 Sn 6 and Nd 2 Au 3 Sn 6 exhibit antiferromagnetic ordering at T N = 6.3(1) and 6.7(1) K. Investigations of the electrical resistivity of La 2 Au 3 Sn 6 and Ce 2 Au 3 Sn 6 confirmed that these compounds are metallic, for La 2 Au 3 Sn 6 a lower resistivity was observed, in line with the absence of screening unpaired electrons. 119 Sn Mössbauer spectra for La 2 Au 3 Sn 6 , Ce 2 Au 3 Sn 6 , Pr 2 Au 3 Sn 6 and Nd 2 Au 3 Sn 6 show a complex superposition of three sub‐spectra which can be differentiated through their distinctly different quadrupole splitting parameters. The isomer shifts (1.87 to 2.22 mm · s –1 ) indicate significant s electron density at the tin nuclei.